Fuel tanks, such as fuel tanks for gasoline powered motor vehicles, and vapor recovery filling systems for such fuel tanks each of which must form a seal between the fuel tank filler tube of the vehicle and the filler nozzle of the filling pump, are subject to over-pressure conditions during refueling due to the occasional failure of the filler nozzle of the filling pump to shut off when the tank has filled. It is desirable to be able to relieve such an over-pressure condition to avoid distortion of the tank or its components which experience the over-pressure condition, and to be able to do so quickly. Heretofore, poppet-type valves have been utilized to relieve an over-pressure condition in a fuel containing vessel, but such valves tend to open too easily or too far, thus permitting venting when it is not required or excessive venting after it is required. Needle-type valves have also been utilized for this purpose, but such valves are subject to misalignment in operation and require a guide or housing of complex construction to prevent such misalignment.